a certain sum become 7 times itself in 9 years at SI. In how many years will it become 49 times of its initial value?
Answer (1)
18th Sep, 2021
As we know,
The formula for S.I = P*R*T/100.
And Amount = P + S.I.
Now,
Let the sum of money be 100 rupees.
In 9 years it becomes 7 times. Therefore,
100×7=700 in 9 years.
Now According to simple interest formula.
A=P(1+rt)
Where A= final amount
P= Principle amount
r= rate.
t= time
Now on putting the values and solving it we get
700=100(1+ 9r)
From this equation we get r= 0.66 or 66.66%
Now putting the values in the equation again to solve for the number of years required to get the initial amount multiplied 49 times.
4900=100(1+66.66t)
Ans t= 0.72 or 72 years
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